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The effect of water deficit on photochemical parameters, hydraulic properties, phytochemical composition and radical scavenging activity were studied on four Olea europaea cultivars (Chetoui, Ouesl...

The impact of intercropping with two different forage crops (legume and grass) on the shoot growth, ion accumulation and some physiological traits of 3-old year olive trees irrigated by high-salinity water (120 mM NaCl) was assessed under greenhouse conditions. Olive plants were subjected to one of the following treatments: TC (control); TG – olive plants intercropped with grass (Oats: Avena sativa L) and TL – olive trees intercropped with legume (Berseem Clover: Trifolium alexandrinum L). Results showed that sodium root:leaf ratio and nitrogen concentration in olive leaves were significantly increased in TL treatment. Olive shoot length and maximum quantum yield of photosystem II (Fv/Fm) were significantly improved by using Berseem Clover as a cover crop. Negative correlation was observed between the total chlorophyll content and the leaf Na+ concentration. On the other hand, polyphenol content was significantly increased in olive leaves when oats were used as cover crops, in relation to the high N-deficiency observed in olive leaves of TG treatment.

The effects of soil amendment with the hydrophilic polymer Stockosorb ® on the physical properties of the soil as well as on physiological parameters (turgor pressure, stomatal conductance, chlorophyll fluorescence) and yield (vegetative growth, fruit characteristics, oil yield and quality) of an established olive crop cultivated under rainfed conditions, were investigated in Tunisia during the 2014 growing season. Stockosorb ® hydrogel was applied by injection in the soil around olive trees (TS) and compared to a control plot (TC) without hydrogel application. The results showed that water content was generally higher in hydrogel amended soils compared to the control soil. The seasonal leaf patch output pressure ( P p ) readings revealed that trees with Stockosorb ® treatment had the highest water status and were moderately stressed in comparison to control trees which were severely stressed due to the poor water status during the vegetative growth and fruiting period. The application of Stockosorb ® in the root zone of olive trees significantly increased midday stomatal conductance ( g s ) and the maximal quantum efficiency (Fv/Fm). Shoot growth, oil yield and rainwater use efficiency were strongly improved by the Stockosorb ® amendment to the soil, however oil quality still within the threshold limits set for an ‘Extra virgin' classified olive oil.

Aim: Despite its therapeutic value almost nothing is known about potential adverse health effects of Olea europea L. We therefore investigated the in vitro toxicity and genotoxicity of leaf extracts of this plant. Material and Methods: Extracts from olive tree leaves were obtained from four different regions in Tunisia. We investigated the in vitro toxicity, genotoxicity and antigenotoxicity of their aqueous extracts using the neutral red (NR) uptake, Vitotox and alkaline comet assays. Results: None of the extracts were found to be toxic and none of them were genotoxic, although some doubt exists for the extract obtained at Meski (North of Tunisia). On the basis of the Vitotox test only, none of the extracts appeared to have antigenotoxic (or cogenotoxic) properties. Discussion: The negative genotoxicity underline the safe use of the leaves, for example, as hypoglycemic and antidiabetic preparations. Lack of antigenotoxicity may indicate that the previously reported anticancer effects do not result from protection against genotoxicity. HIGHLIGHTS We investigated the in vitro toxicity and genotoxicity of aqueous extracts of olivesThe neutral Red Uptake test, Vitotox and alkaline comet assay were usedLeaf extracts from 4 different origins were investigatedNone of them showed in vitro toxicity or genotoxicityThe extracts also didn’t have antigenotoxic properties Abbreviation list: BaP: benzo(α)pyrene, EMS: ethyl methane sulfonate, LMP: low melting point, NI50: 50% inhibition of NRU, NR: neutral red, NRU: neutral red uptake, OD: optical density, PBS: phosphate buffer saline, SDS: sodium dodecyl sulphate, S/N: signal to noise ratio, 4NQO: 4-nitroquinoline oxide

Plant water relations and their dependence on microclimate and soil moisture were studied during 45 days in young olive trees cvs Chemlali and Chetoui subjected to a drying period and rehydration. The recently developed leaf patch clamp pressure (LPCP) probe were used for monitoring turgor-dependent leaf patch pressures ( P p) and compared with some conventional methods to detect water stress. Results show that, in well-watered olive plants, diurnal Pp is highly linearly correlated with vapour pressure deficit (VPD). Pp night readings gradually increased with increasing soil drought and revealed the beginning of water stress. At the end of the drying period, when the soil water content reach values less than the wilting point, only Pp curves detect the water stress in the two olive cultivars before the others methods tested here (ex: relative water content, chlorophyll content, chlorophyll fluorescence and stomatal conductance). Non-destructive, continuous leaf turgor pressure method showed promising potential for monitoring and detecting early water stress of young olive tree, in spite of sensibility to water stress, technological and data interpretation challenges requiring further attention.

The use of wastewater (WW) provides a reliable source of water and nutrients for crop production. Soil tillage is one of the key soil management practices in agricultural land use. In the present study, we studied the effects of these two agricultural practices on key physiological parameters of olive trees and on olive oil quality. The experiment was carried out on mature olive trees (Olea europaea L. cv. Chemlali). Two tillage practices treatments (Trees grown in Tilled soil: TTS; and Trees grown in No-tilled soil: TNTS) were combined with two irrigation treatments (Trees irrigated with WW: IT; and Trees grown under rainfed condition: TRC) during two successive years (2013 and 2014). Statistical analyses demonstrated that the factor “soil tillage” was more efficient in improving photosynthetic parameters of olive trees than WW irrigation. The combination of soil tillage with WW irrigation improved significantly leaf chlorophyll fluorescence parameters, stomatal conductance, transpiration and chlorophyll content, which closely associated with an increase of photosynthetic rate, and a decrease of stress metabolites (leaf phenolic compounds and carbohydrates). On the other hand, a decrease of key photosynthetic parameters and an accumulation of stress metabolites in leaves were observed when combining rainfed condition and No-tilled soil. WW irrigation affected negatively the oxidative stability and nutritional value of olive oil, especially by decreasing the contents of antioxidant compounds (total phenols and pigments) and the levels of MUFA, C18:1, C18:3 and elevating SFA and PUFA contents. However, soil tillage combined with TRC improved oil stability to oxidation and its nutritional value by increasing the contents of antioxidant compounds and the levels of MUFA and C18:1, as well as C18:1/C18:2 and MUFA/PUFA ratios. The results of this study prove that, under water scarcity conditions, wastewater irrigation in oleiculture should be combined with soil tillage and recommended only in the ‘Off’-year to support vegetative growth and improve physiological performance of olive trees. In the ‘On’-year, tilling the soil under rainfed conditions proved to be the most favorable cropping strategy for enhancing both physiological performance of olive trees and olive oil quality. These findings must be taken into consideration when developing strategies for oil quality enhancement, mainly in an exporting country like Tunisia.

Predicting photosynthetic production in olive trees is a key feature in managing the effect of climate change on arid areas. Functional-structural plant modelling is a promising tool for achieving this goal. We used a photosynthetic sub-model that accounted for water and temperature stress and implemented it into LIGNUM model. We then conducted an experiment to validate the model at the leaf level using olive trees (Olea europaea) grown under various climatic condition. Then, we simulated photosynthetic production of three static olive tree models aged 1, 2, and 3 years. Results revealed a good fit between observed and predicted photosynthesis, with coefficient of determination (R2) values of 0.94 and 0.93 for Chemlali and Zarrazi cultivars, respectively. These results showed that the impact of water stress on photosynthetic production was marginal.

Abiotic stresses present a real environmental problem in agriculture field. In our paper, we examine the significance of arbuscular mycorrhizal fungi (AMF) and soil amendment with water retaining superpolymers (hydrogel) on growth and physiology performance of olive plantlets. Our experiment was carried out in nursery conditions, to test the impact of hydrogel (TH) and mycorrhizal fungi (TM), used individually or combined (THM), and compare them with non inoculated plants (TC), to understand and reduce the water stress damage in olive plantlets (cv. Chemlali). We also evaluate interactions between hydrogel, mycorrhizal treatments and water regimes. Results of mycorrhization (M%) show that roots colonized by Rhizophagus irregularis of well-watered plants were about 40.87%. In combined treatment (THM), M% was about 32.14%. Compared to TC treatment, TM treatment enhances significantly the dry weights of the whole plant under the two water regimes. The TM treatment had the highest relative water content (66.50%) and Chl (a + b) (0.83 mg g− 1) in stressed conditions. We found also that under water stress, the maximal quantum efficiency of the photosystem II measurements in leaves were significantly improved by 50.70% in TH treatment compared to control. For phenolic contents, TH treatment decreased significantly total phenols by 50.10% compared to TC. Our study gives evidence that the use of AMF and the hydrogel separately or in combination may enhance the capacity to avoid drought damages of olive plantlets and improve olive performances.

We studied changes in morphology, sclerophylly, chlorophyll photosynthetic parameters and total phenol contents in leaves of three olive (Olea europaea L.) cultivars; Oueslati, Jarboui and Meski which grew under water deficit conditions. Our results showed significant differences in trichome and stomatal densities, area of the leaf and relative surface of stomatal pores. The photosynthetic parameters Fv/Fm, Phi PSII and ETR were negatively affected by the water deficit in these three varieties. The total phenolic and flavonoid contents increased in all cultivars, with Oueslati showing the highest values. The Oueslati variety could be considered as the most drought-tolerant compared to Jarboui and Meski. Therefore we believe this cultivar is the most suitable for cultivation in semi-arid environments. (c) 2018 SAAB. Published by Elsevier B.V. All rights reserved.

The experiment was carried out on olive trees cv. Chemlali, during two successive years (2013/2014). Two irrigation treatments (IT: Trees irrigated with wastewater; TRC: Trees grown under rainfed condition) were combined with two tillage practices (TTS: Trees grown in tilled soil; TNTS: Trees grown in non-tilled soil).; Results: The results of the study showed that wastewater irrigation combined with soil tillage improved the pomological characteristics of olive fruits. The tree yield increase was substantial for IT and TTS. However, most of the identified phenolic compounds, especially oleuropein, mainly accumulated in olive fruits of the TC block (TNTS + TRC), suggesting a marked improvement in the nutritional value of these fruits. Moreover, fruits of TNTS had high contents of sugar compounds, required for the synthesis of the fruit storage material. The study also showed that the agronomic practices affected the amounts of some aromatic compounds responsible for the distinctive flavour notes of olive oil.; Conclusion: Agronomic practices may affect considerably the commercial and nutritional values and the sensorial quality of the commodities. © 2017 Society of Chemical Industry.; © 2017 Society of Chemical Industry.

Chlorophyll content, fluorescence parameters, xylem hydraulic properties, total phenolic content and antiradical activity were studied on young plants of four Tunisian olive cultivars (Chetoui, Ouslati, Jarboui and Meski) grown under water deficit conditions for two months. Water stress caused a decline in chlorophyll content, in maximum quantum yield of photosystem II (Fv/Fm), in linear electron transport rate (ETR) and in quantum efficiency of PSII electron transport (Φ PSI). Chetoui variety was the less affected by water stress but all these parameters decreases considerably in Ouslati, Jarboui and Meski. In all cultivars, water stress induced an increase in xylem vessel frequency. Water stress also increased the phenolic and flavonoid contents and antiradical activity in all cultivars. Chetoui cultivar may be considered as the most tolerant cultivars among the tested cultivars showing higher phenolic and flavonoid contents and an important antiradical activity under water deficit. Meski cultivar is the most sensitive one.

Most of the studies investigated the effects of nutrient-based fertilizers on olive fruits and oil quality; few studies have been interested in the modification of the chemical composition of olive leaves in response to fertilization. Thus, the current study aims to examine the effects of foliar fertilization on the mineral profile of olive leaves as well as the concentrations of chlorophyll, antioxidants (phenolic compounds) and carbohydrates. Experimentation consists of the annual application of six treatments during two successive growing seasons (2009–2010): TC (untreated trees), P1 (nitrogen-based fertilizer), P2 (contains boron, magnesium and manganese), P3 (phosphorus and potassium based fertilizer), P4 (rich in calcium and phosphorus), T5 (P1 and P2 application) and T6 (P1, P2, P3 and P4 application). At the end of the experiment, mineral analysis of olive leaves showed an increase in the concentrations of most nutrients which induced changes in biochemical composition: an increase of chlorophyll content, a reduction of total phenols and oleuropein concentrations coupled with an increase of hydroxytyrosol level. Moreover, an increase of total sugar content and most individual sugars, principally translocated forms of sugars (mannitol, sucrose and raffinose), was also observed. The accumulation of these key physiological parameters by foliar fertilization suggests an improvement of physiological performance and photosynthetic capacity of olive trees. Moreover, from a biological point of view, the results of the study revealed the possibility to improve plants of medicinal interest by enhancing the accumulation of some bio-active compounds, such as hydroxytyrosol and mannitol, via foliar nutrient supply.

Since antiquity, the Meskat system was adopted practice to sustain olive tree cultivation in the Tunisian Sahel region. This technique was based on the runoff harvesting from catchment area to irrigate downstream plots planted with olive trees as blocks. This paper aims to study the spatial distribution and characterization of Meskat system. A set of maps and satellite data were used and integrated into a geographic information system to perform the inventory of the Meskat system used in Sousse region. The sizing of this system was based on the estimation of the ratio between a catchment area (impluvium) and the cropped area of each entity, called “K ratio”. The results showed that Meskat system is implemented in five watersheds in Sousse region; especially Wadi Hamdoun watershed is the most fitted. Meskats are installed, mostly, on soils characterized by medium to fine textures, poorly suitable for infiltration. The K ratios vary from 0.04 to 6.62 with 0.76 as average. For all Meskat system 87% had K ratio less than 1.5 which is the ideal ratio for optimum olive production, indicating that the system seems to be undersized.